CVE-2026-63201
netopeer2-server logging has format string vulnerability via subtree filter
Description
Netopeer2 is a server for implementing network configuration management based on the `NETCONF` Protocol. In affected versions, a low-privileged authenticated `NETCONF` user can remotely crash `netopeer2-server` by sending a `get RPC` with an invalid `subtree filter` whose text contains format specifiers. In `src/netconf.c`, `np2srv_rpc_get_cb()` sends the invalid value through `ERR()` to `np2log_printf()`, where `vsnprintf()` first formats the message safely. In `src/log.c`, that already formatted buffer is subsequently passed to `np2log()` as the format string itself, causing `vsyslog()` to interpret attacker-controlled percent sequences and read invalid pointer arguments. The reported denial of service was confirmed on version 2.8.7 using `NETCONF`-over-SSH and AddressSanitizer; reliable remote code execution was not confirmed. `The advisory identifies 2.8.8 as patched`; repository comparisons verify the fix in public release 2.8.21. The affected/fixed boundary remains unresolved because no public 2.8.8 tag was located, which does not establish the status of an untagged 2.8.8 build.
INFO
Published Date :
Oct. 30, 2026, 10:16 p.m.
Last Modified :
Oct. 30, 2026, 10:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-63201
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Netopeer2 to version 2.8.21 or later.
- Apply patches provided by the vendor.
- Ensure the server is configured securely.
- Monitor server logs for suspicious activity.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63201.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63201 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-63201
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-63201 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63201 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Oct. 30, 2026
Action Type Old Value New Value Added Description Netopeer2 is a server for implementing network configuration management based on the `NETCONF` Protocol. In affected versions, a low-privileged authenticated `NETCONF` user can remotely crash `netopeer2-server` by sending a `get RPC` with an invalid `subtree filter` whose text contains format specifiers. In `src/netconf.c`, `np2srv_rpc_get_cb()` sends the invalid value through `ERR()` to `np2log_printf()`, where `vsnprintf()` first formats the message safely. In `src/log.c`, that already formatted buffer is subsequently passed to `np2log()` as the format string itself, causing `vsyslog()` to interpret attacker-controlled percent sequences and read invalid pointer arguments. The reported denial of service was confirmed on version 2.8.7 using `NETCONF`-over-SSH and AddressSanitizer; reliable remote code execution was not confirmed. `The advisory identifies 2.8.8 as patched`; repository comparisons verify the fix in public release 2.8.21. The affected/fixed boundary remains unresolved because no public 2.8.8 tag was located, which does not establish the status of an untagged 2.8.8 build. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-134 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/63xxx/CVE-2026-63201.json">CVE-2026-63201</a> Added Reference https://github.com/CESNET/netopeer2/commit/e98beb2d4d8cc82875208bccb8e1348a8e9e95b3 Added Reference https://github.com/CESNET/netopeer2/releases/tag/2.8.21 Added Reference https://github.com/CESNET/netopeer2/security/advisories/GHSA-25gm-4x89-7r2q